1. Technical Field of the Invention
The present invention relates to a method for manufacturing an insert molding, and particularly relates to a method for manufacturing an insert molding in which a portion of a conductor member other than a contact point can be coated with a thin film surely.
2. Description of the Related Art
In a terminal 30 for connecting an electric equipment of a car, a pair of bus bars 31 are insert-molded with resin having an insulating characteristic as shown in FIGS. 3(A) to 3(C).
The bus bars 31 are made into suitable metal plate members having electrical conductivity, and disposed in parallel with each other along the axial direction of identical columnar circumferential surface in the state where the respective end portions of the bus bars 31 have been trued up. These bus bars 31 are projecting outside from a coating 32 in order to make their respective one end portions act as contact points.
In manufacturing such a terminal 30, in connection with coating, it is necessary to keep the relative positions of the bus bars 31, or the relative positions of the bus bars 31 and a mold accurately because the bus bars 31 are coated with a thin film.
Conventionally, thus the terminal 30 was manufactured in a manner such that the longitudinal center portions of the bus bars 31 were grasped between upper and lower mold parts of a mold into which resin is to be injected, and then resin is injected into the mold.
In the above-mentioned method for manufacturing the terminal 30, however, exposed portions 33 which were not coated with the coating 32 were formed because the longitudinal center portions of the bus bars 31 were fixed by the upper and lower mold parts.
Therefore, in the thus manufactured terminal 30, there was a fear that the terminal 30 or other parts were damaged or short-circuited because of the exposed portions 33 of the bus bars 31.
The present invention has been achieved in view of the foregoing problem, and it is an object thereof to provide a method for manufacturing an insert molding in which in a conductor member, that portion of a conductor member other than a contact point can be coated with a thin film surely.
In order to achieve the above object, there is provided a method for manufacturing an insert molding having a conductor member in which a part thereof is coated with resin comprising the steps of: securely supporting a part of the conductor member by a fixation member provided in a holding member; grasping the holding member supporting the conductor member by a mold so as to accommodate a portion of the conductor member where is other than a portion to be utilized as a contact point; injecting the resin into inside of the mold; and coating the conductor member accommodated in the mold integrally with the holding member by the resin.
In the method for manufacturing the thus configured insert molding, the conductor member is held by a holding member grasped in the mold. Accordingly, it is possible to held the relative positions of the conductor member and the mold when molten resin is injected into the mold. This holding member is integrated with a thin film as the molten resin injected into the mold is solidified, and there is no fear that the holding member projects out from the surface of the thin film.
That is, in this method for manufacturing insert molding, the holding member for holding the conductor member is integrated with the thin film, so that partially exposed portions conventionally formed in the conductor member can be eliminated.
Preferably, the holding member may be made from the same material as the resin, so that the appearance of insert molding is improved.
In the holding member, the fixation portion may be formed substantially into a C-shape so as to be capable of grasping the conductor member.
Here, as for the fixation portion, for example, in order to grasp a band-like conductor member, any shape will do so long as the gap size of the fixation portion set to be a little smaller than the thickness size of the conductor member so that the conductor member can be grasped by the elastic deformation of the holding member.
In the method, a convex portion may be formed in one of the conductor member and the holding member and engaged with the other member at the time of supporting.
Here, as for the convex portion, in the case where the conductor member is, for example, like a band, a protrusion may be formed by pressing the plate of the conductor member, a protrusion may be formed integrally with an end surface when the conductor member is formed by punching, or the like. Then, the protrusion may be engaged with an edge portion of the fixation portion for fixing the conductor member, may be pressed onto the inner surface of the fixation portion, or may be engaged with a concave portion provided in the inner surface of the fixation portion. On the other hand, as for the convex portion provided in the holding member, for example, a protrusion may be formed in the inner surface of the fixation portion for fixing the conductor member. Then, the protrusion may be engaged with a recess portion, a notch, a hole, or the like, formed in the conductor member.
In such a method for manufacturing insert molding, a convex portion provided in one of the conductor member and the holding member is engaged with the other. Accordingly, the relative positions of the conductor member and the holding member are kept surely.
On the other hand, the fixation portion may be formed as an insertion hole to which the conductor member is inserted. According to this configuration, the conductor member can be fixed surely regardless of the injection speed of molten resin injected into the mold.
In addition, the holding member may be formed so as to be brought into face contact with an inner wall face of the mold. According to this configuration, the holding member can be grasped firmly regardless of the injection speed of molten resin injected into the mold.
The holding member may be formed so as to be brought into line or point contact with an inner wall face of the mold. According to this configuration, it is possible to reduce the area where the holding member is exposed from the surface of the coating, so that it is possible to improve the appearance of insert moldings.
As for the conductor members, a pair of metal band portions adopted in the above-mentioned terminal may be shown by way of example. However, according to the present invention, rod or rectangular conductor members are also supposed, and the conductor members are not required to be identical in shape to each other are not required to be disposed in parallel with each other. In addition, the present invention can be applied not only to the case where two conductor members or more are coated with a thin film, but also to the case where a single conductor member is coated with a thin film.